Diet Is a Small Contributor to Interindividual Variation of Urinary Free Catecholamines and Related Metabolites Determined by LC-MS/MS for the Screening of Catecholamine-Secreting Tumors

Pheochromocytomas and paragangliomas (PPGL) are rare neuroendocrine tumors of the adrenal medulla or sympathetic nerves causing paroxysmal hypertension, severe headaches, sweating and palpitations. These symptoms, caused by fluctuant and excessive catecholamines releases, can be fatal for the patient. Neuroblastomas are also neuroendocrine tumors developed from neural crest-derived tissues, sometimes secreting catecholamines and affecting young children. Physical examination, imaging, and biochemical tests are used for diagnosis. Biological diagnosis of PPGL is contingent on a 4-fold increase in 24-h urinary fractionated metanephrines or plasma fractionated metanephrines above the upper reference limit (URL) (1); a 2- to 4-fold increase, while raising concern, requires more in-depth investigations to establish the diagnosis. Similarly, diagnosis of neuroblastoma is based on increased urinary catecholamines (mostly dopamine), homovanillic acid (HVA), and vanylmandelic acid (VMA). Although de Jong et al. have previously shown urinary free catecholamine metabolites to be less affected by diet (2), a restrictive diet devoid of any food containing high amounts of biogenic amines (3) is still recommended prior to urine collection. These restrictions not only are unpleasant for the patient, but also can delay the anticipated results for up to 3 days. In this study, we investigated the impact of catecholamine-rich food consumption on the urinary free metanephrines, dopamine, HVA, and VMA using liquid chromatography with tandem mass spectrometry (LC-MS/MS).